1. Field of the Invention
This invention relates to a damper which can damp vibration generated mainly by a vibratory body and more particularly relates to a damper comprising a high polymer sheet which contains piezoelectric ceramic powder and a cloth layer placed therein which essentially comprises carbon fibers, and this invention further relates to a method for producing such a damping composition.
2. Description of the Prior Art
In a conventional damper which transforms the vibratory energy generated by a vibratory body into electrical energy, which is then to be transformed into thermal energy to be dissipated, said vibratory energy is transformed into electrical energy by means of a piezoelectric body functioning as a medium to which an external resistor or external resistors are at times connected as a medium for transforming said electrical energy into thermal energy.
The connection work of such external resistors to a piezoelectric body, however, often becomes a cause of trouble, and further such external resistors usually extrude from a piezoelectric body obstructing attachment of a damper to a vibratory body, resulting in limitation to the use of such a damper.
Recently a piezoelectric body with carbon powder or the like mixed therein instead of using an external resistor was proposed (Japanese Patent Publication No. 61-46498).
Said piezoelectric body containing carbon powder or the like does solve said trouble caused by installation of external resistors, however, it possesses the following shortcomings:
a) it is technically hard to evenly mix carbon powder or the like in a piezoelectric body, resulting in dispersion of resistivity per manufactured damping body, therefore leading to inconsistency of damping effects; and PA1 b) it takes relatively a long time (30 min. to 60 min.) to mix carbon powder or the like well in a piezoelectric body, resulting in lowering productivity.